Wireless local area network with repeater for enhancing network coverage

ABSTRACT

In a wireless communications network such as a WLAN, a frequency translating repeater ( 200, 204 ) facilitates and enhances wireless communication between a first communication device ( 100 ) and one or more second client unit ( 104, 105 ) using frequency translation and retransmission based on modified protocol messages ( 410 ). A DS parameter message ( 310 ) may include a frequency channel intended for use between one or more of repeaters ( 200, 204 ) and client units ( 104, 105 ) but does not include the frequency channel between one or more of repeaters ( 200, 204 ) and the first communication device ( 100 ).

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is related to PCT Application PCT/US03/16208 entitledREPEATER FOR WLAN, and is further related to and claims priority fromU.S. provisional Application Ser. No. 60/414,888, filed on Oct. 1, 2002both of which are incorporated herein by reference.

FIELD OF THE INVENTION

The present invention relates generally to wireless local area networksand more specifically to increasing the range of a wireless local areanetwork (WLAN).

BACKGROUND OF THE INVENTION

Several standard protocols for wireless local area networks, commonlyreferred to as WLANs, are becoming popular. These include protocols suchas 802.11 (as set forth in the 802.11 wireless standards), home RF, andBluetooth. The standard wireless protocol with the most commercialsuccess to date is the 802.11b protocol.

While the specifications of products utilizing the above standardwireless protocols commonly indicate data rates on the order of, forexample, 11 MBPS and ranges on the order of, for example, 100 meters,these performance levels are rarely, if ever, realized. Performanceshortcomings between actual and specified performance levels have manycauses including attenuation of the radiation paths of RF signals, whichare typically in the range of 2.4 GHz in an operating environment suchas an indoor environment. Base or AP to receiver or client ranges aregenerally less than the coverage range required in a typical home, andmay be as little as 10 to 15 meters. Further, in structures having splitfloor plans, such as ranch style or two story homes, or thoseconstructed of materials capable of attenuating RF signals, areas inwhich wireless coverage is needed may be physically separated bydistances outside of the range of, for example, an 802.11 protocol basedsystem. Attenuation problems may be exacerbated in the presence ofinterference in the operating band, such as interference from other 2.4GHz devices or wideband interference with in-band energy. Still further,data rates of devices operating using the above standard wirelessprotocols are dependent on signal strength. As distances in the area ofcoverage increase, wireless system performance typically decreases.Lastly, the structure of the protocols themselves may affect theoperational range.

One common practice in the mobile wireless industry to increase therange of wireless systems is through the use of repeaters. However,problems and complications arise in that system receivers andtransmitters may operate at the same frequency in a WLAN utilizing, forexample, 802.11 or 802.16 WLAN wireless protocol. In such systems, whenmultiple transmitters operate simultaneously, as would be the case inrepeater operation, difficulties arise. Other problems arise in that,for example, the random packet nature of typical WLAN protocols providesno defined receive and transmit periods. Because packets from eachwireless network node are spontaneously generated and transmitted andare not temporally predictable packet collisions may occur. Someremedies exist to address such difficulties, such as, for example,collision avoidance and random back-off protocols, which are used toavoid two or more nodes transmitting packets at the same time. Under802.11 standard protocol, for example, a distributed coordinationfunction (DCF) may be used for collision avoidance.

Such operation is significantly different than the operation of manyother cellular repeater systems, such as those systems based on IS-136,IS-95 or IS-2000 standards, where the receive and transmit bands areseparated by a deplexing frequency offset. Frequency division duplexingor multiplexing, (FDD or FDM), operation simplifies repeater operationsince conflicts associated with repeater operation, such as thosearising in situations where the receiver and transmitter channels are onthe same frequency, are not present.

Other cellular mobile systems separate receive and transmit channels bytime rather than by frequency and further utilize scheduled times forspecific uplink/downlink transmissions. Such operation is commonlyreferred to as time division duplexing or multiplexing, e.g. TDD or TDM.Repeaters for these systems are easily built, as the transmission andreception times are well known and are broadcast by a base station.Receivers and transmitters for these systems may be isolated by anynumber of means including physical separation, antenna patterns, orpolarization isolation.

Thus, WLAN repeaters operating on the same frequencies with, forexample, TDD but no scheduling are presented with unique constraints dueto the spontaneous transmission capabilities of network nodes andtherefore require a unique solution. Further, in cases where uplink anddownlink times are known, repeaters configured to ignore scheduleinformation may be less costly to build. Thus some form of isolationmust exist between the receive and transmit channels of WLAN repeatersusing the same frequency for both channels. While some related systemssuch as, for example, CDMA systems used in wireless telephony, achievechannel isolation using sophisticated techniques such as directionalantennas, physical separation of the receive and transmit antennas, orthe like, such techniques are not practical for WLAN repeaters in manyoperating environments such as in the home where complicated hardware orlengthy cabling is not desirable or may be too costly.

One system, described in International Application No. PCT/US03/16208and commonly owned by the assignee of the present application, resolvesmany of the above identified problems by providing a repeater whichisolates receive and transmit channels using a frequency detection andtranslation method. The WLAN repeater described therein allows two WLANunits to communicate by translating packets associated with one deviceat a first frequency channel to a second frequency channel used by asecond device. The direction associated with the translation orconversion, e.g. from the frequency associated with the first channel tothe frequency associated with the second channel, or from the secondchannel to the first channel, depends upon a real time configuration ofthe repeater and the WLAN environment. The WLAN repeater may beconfigured to monitor both channels for transmissions and, when atransmission is detected, translate the received signal at the firstfrequency to the other channel, where it is transmitted at the secondfrequency.

The above described approach solves both the isolation issue and thespontaneous transmission problems as described above by monitoring andtranslating in response to packet transmissions and may further beimplemented in a small inexpensive unit. However, due to requirementsassociated with the WLAN protocols, the effectiveness of the previouslymentioned solution may be limited. For example, the IEEE 802.11 standardrequires that an access point transmit a channel identifier indicatingthe channel upon which the AP is communicating in a protocol messagecommonly referred to as a beacon. The frequency translating repeater inthe above identified application retransmits the beacon on a differentchannel from the original AP channel. In addition, packets from the APare transmitted on the same channel as the translated beacon, e.g. thetranslated frequency. Problems arise in that the beacon identifies thatassociated packets are being transmitted on the original AP transmissionfrequency and not the translated frequency. A client unit receiving thebeacon may switch to the original AP transmission frequency contained inthe beacon and miss packets sent by the repeater on the translatedfrequency or may discard the beacon preventing a client from connecting.

SUMMARY OF THE INVENTION

Thus a method and apparatus for extending the range of a wireless localarea network (WLAN), are described, wherein in accordance with oneexemplary embodiment, the WLAN includes a base unit connected to a widearea network. The base unit communicates with at least one client unitusing a protocol requiring the base unit and the at least one clientunit to receive and transmit information on a same frequency channel,e.g. an 802.11, or the like protocol, the frequency channel chosen fromat least two available frequencies. The base unit preferably identifieswhich of frequencies is chosen in a control parameter transmitted in aprotocol message associated with the protocol.

In accordance with various exemplary embodiments, the present inventionincludes a technique for performing range extension utilizing repeatersfor wireless local area networks including attendant advantages ifspecific protocols are used, such as the 802.11 protocol. In accordancewith the present invention, MAC protocol messages, such as, for example,DS parameter messages, may be modified and used in a non-standard way.Combined with the use of frequency translating repeaters, the presentinvention allows for greater isolation and increased gain and hencerange in a wireless local area network.

As previously described, some revisions of 802.11 include a messagereferred to as the DS parameters set message. It should be noted that inaccordance with the present invention, the beacon is only transmitted bythe AP, not by client units or stations. The DS parameter specifieswhich channel the direct sequence spread spectrum wave form (802.11b) istransmitted on. Using a frequency translating repeater will cause thechannel number to be incorrect relative to the DS parameter causingerroneous behavior for the client units or station devices (STA). In thepresent invention, the transmitted DS parameters set message ispreferably modified with the channel number intended for the STA, ratherthan the channel that is transmitted on from the access point (AP). Thetranslating repeater will then “correct” the message by performing thefrequency translation, which will result in the message beingretransmitted on the frequency identified in the beacon transmitted fromthe AP.

Interestingly, the above technique provides for beneficial systemarrangements. Specifically, the channel from the AP to the repeater canbe preserved for use by the AP, while the channel from the repeaters toclient devices are separately allocated. For this application, thechannel from the AP to the repeater, with the incorrect DS Parameter setmessage, is referred to as the back haul channel. The translatingrepeater to client station channel is referred to as the off-ramprepeater. Further, highway repeaters may be utilized between the AP andthe client stations to extend the wireless local area network evenfurther.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram illustrating a wireless network environmentincluding an exemplary repeater.

FIG. 2 is a block diagram illustrating an alternative wireless networkenvironment including two exemplary repeaters.

FIG. 3A a diagram illustrating packet configurations for variousexemplary protocol units in a wireless local area network (WLAN).

FIG. 3B a diagram illustrating additional packet configurations forvarious exemplary protocol units in a wireless local area network(WLAN).

FIG. 4 is a diagram illustrating channel identifier packet transmissionbetween units in accordance with various exemplary embodiments of awireless local area network (WLAN) in accordance with the presentinvention.

DETAILED DESCRIPTION OF THE INVENTION

Referring now to FIG. 1, a wide area connection 101, which could be anEthernet connection, a T1 line, a wideband wireless connection or anyother electrical connection providing data communications, may beconnected to a wireless gateway, or access point 100. The wirelessgateway 100 sends RF signals, such as IEEE 802.11 packets or signalsbased upon Bluetooth, Hyperlan, or other wireless communicationprotocols, to client units 104, 105, which may be personal computers,personal digital assistants, or any other device capable ofcommunicating with other like devices through one of the above mentionedwireless protocols. Respective propagation, or RF, paths to each of theclient units are shown as 102, 103.

While the signal carried over RF path 102 is of sufficient strength tomaintain high-speed data packet communications between the client unit104 and the wireless gateway 100, the signals carried over the RF path103 and intended for the client unit 105 would be attenuated whenpassing through a structural barrier such as a wall 106 to a point wherefew, if any, data packets are received in either direction if not for awireless repeater 200, the structure and operation of which will now bedescribed.

To enhance the coverage of the wireless gateway 100, and therefore theoverall wireless network, and/or communication data rate to the clientunit 105, the wireless repeater 200 receives packets transmitted on afirst frequency channel 201 from the wireless gateway 100. The wirelessrepeater 200, which may have dimensions of, for example, 2.5″×3.5″×0.5″,and which preferably is capable of being plugged into a standardelectrical outlet and operating on 110 V AC power, detects the presenceof a packet on the first frequency channel 201, receives the packet andre-transmits the packet with more power on a second frequency channel202. Unlike conventional WLAN operating protocols, the client unit 105operates on the second frequency channel, even though the wirelessgateway 100 operates on the first frequency channel. To perform thereturn packet operation, the wireless repeater 200 detects the presenceof a transmitted packet on the second frequency channel 202 from theclient unit 105, receives the packet on the second frequency channel202, and re-transmits the packet on the first frequency channel 201. Thewireless gateway 100 then receives the packet on the first frequencychannel 201. In this way, the wireless repeater 200 is capable ofsimultaneously receiving and transmitting signals as well as extendingthe coverage and performance of the wireless gateway 100 to the clientunit 105.

It should also be appreciated that wireless repeater 200 may be used toenhance communications in a peer-to-peer network from one client unit toanother client unit. In a scenario where many units are isolated formone another, wireless repeater 200 preferably acts as a wireless huballowing two different groups of units to communicate in such anisolated environment where communication in accordance with standard RFpropagation and coverage rules would otherwise be inhibited.

However, as described herein above, repeater systems using frequencytranslation may encounter problems, for example, when beacon signals areused. In accordance therefore with the present invention, rangeextension may be realized in such systems using repeaters for wirelesslocal area networks and may be particularly advantageous when specificprotocols are used, such as, for example, the 802.11 series of protocolsby modifying the beacon signal to reflect the frequency translation. Inaccordance with various exemplary embodiments thereof, the presentinvention further includes the use of medium-access control (MAC)protocol messages modified in a novel manner. Thus, frequencytranslating repeaters may be used to allow for greater isolation andincreased gain and resulting in greater range in a wireless local areanetwork.

In some versions of the 802.11 standard, a message referred to as the DSparameters set may be associated with the transmission of a beaconsignal as described herein above. It is important to note that a beaconsignal is generally transmitted by an access point (AP), and not byindividual nodes or stations. The DS parameter specifies which channelthe direct sequence spread spectrum waveform, for example, as specifiedin 802.11b, is transmitted on. The use of a frequency translatingrepeater will cause a discrepancy between the actual transmit channelnumber, e.g. the “translated to” channel number, and the channelspecified in the DS parameter, e.g. the “translated from” channelnumber, causing traffic loss and other erroneous behavior for clientstation devices (STA).

In contrast, an exemplary frequency translating repeater in accordancewith various exemplary embodiments of the present invention, modifiesthe DS parameters to update the channel number, e.g. frequency, with thenew channel number based on frequency translation that will be performedwith subsequent data packets transmitted on that channel number from asource or AP. The translating repeater then “corrects” the message byperforming the frequency translation resulting in the message beingretransmitted on the frequency identified in the beacon transmitted fromthe AP at the destination.

Interestingly, the present invention provides for beneficial systemarrangements wherein, for example, the channel number from the AP to therepeater may be preserved for use by the AP to repeater link, while thechannel number from the repeater or repeaters to client units areseparately allocated. Further in accordance with the present invention,the channel number from the AP to the repeater, e.g. the one having theincorrect DS Parameter set message, may be referred to as the back haulchannel. The translating repeater, e.g. the repeater communicating withthe client station or stations may be referred to as the off-ramprepeater. Still further, one or more highway repeaters may be usedbetween the AP and the stations to extend the wireless local areanetwork even further.

Referring again to FIG. 1, as described herein above, wide areaconnection 101 is preferably connected to a wireless gateway or accesspoint (AP) 100. AP 100 communicates by transmitting and receiving, forexample, data packets to wide area connection 101 on one side and sendsRF signals 102 and 103, to client units 104 and 105. In accordance witha preferred embodiment, RF signals 102 and 103 preferably carry, forexample, IEEE 802.11 packets. In accordance with alternative exemplaryembodiments, RF signals 102 and 103 could also be associated withBluetooth, Hyperlan, or the like wireless communication protocols. Twopropagation paths to each of the client units are further shownassociated with RF signals 102 and 103. It should be noted that whilethe signal strength resulting from the path associated with RF signal102 is sufficient to maintain high speed data packet communications withclient unit 104, the signal strength resulting from the path associatedwith RF signal 103 however is attenuated, e.g. from obstacle 106 whichmay be a wall or other obstruction, to a level where few or no datapackets are able to be received in either direction between, forexample, AP 100 and client unit 105.

To address the difficulties posed by obstructions as described above andattendant attenuation of the signal strength along obstructed paths andthus to enhance the coverage and/or communication data rate to clientunit 105, exemplary wireless repeater 200, as shown in FIG. 1, may beused to retransmit packets beyond a range limited by propagation pathconstraints through, for example, frequency translation. Packetstransmitted on a first frequency channel 201 from AP 100 are received atrepeater 200 and re-transmitted, preferably with a greater power level,on a second frequency channel 202. Client unit 105 preferably operateson second frequency channel 202 as if AP 100 were also operating on it,e.g. with no knowledge that AP 100 is really operating on firstfrequency channel 201 such that the frequency translation istransparent. To perform return packet operations, repeater unit 200detects the presence of a transmitted return packet on second frequencychannel 202 from client unit 105, and is preferably configured toreceive the packet on second frequency channel 202, retransmitting them,for example to AP 100, on first frequency channel 201. Repeater 200 maythus receive and transmit packets at the same time on differentfrequency channels extending the coverage and performance of theconnection between AP 100 and client unit 105, peer-to-peer connections,e.g. from one client unit to another client unit. When many units areisolated from one another in the communication environment, repeaterunit 200 further acts as a wireless bridge allowing two different groupsof units to communicate, where optimum RF propagation and coverage or inmany cases any RF propagation and coverage was not previously possible.

Thus in accordance with various exemplary embodiments, wireless repeater200 is preferably capable of receiving two different frequenciessimultaneously, e.g. first frequency channel 201 and second frequencychannel 202 determining which channel is carrying a signal associatedwith, for example, the transmission of a packet, translating from theoriginal frequency channel to an alternative frequency channel andretransmitting the frequency translated version of the received signalon the alternative channel. Details of internal repeater operation maybe found in co-pending PCT Application No. PCT/US03/16208.

Referring still to FIG. 1, and in accordance with one preferredexemplary embodiment of an 802.11 system, a beacon message transmittedfrom AP 100 to another device has a specific field, e.g. the channelnumber field of a DS parameter set. However the channel numberidentified in the beacon transmitted from AP 100, for example, torepeater 200, does not correspond to the actual channel number usedbetween AP 100 and repeater 200, e.g. channel 201. Rather, in accordancewith the present invention, the channel of operation identified in thebeacon from AP 100 is the channel to be used after frequency translationoccurs in repeater 200, which will be referred to hereinafter asfrequency translating repeater 200. More specifically, a signal could bemodulated as a IEEE 802.11b waveform within AP 100, but transmitted onthe incorrect band as defined by the IEEE 802.11a standard at afrequency of 5 GHz. It should be apparent to one of ordinary skill inthe art how to transmit the signals on the frequencies described hereinaccording to the protocols set forth, and, further, the DS parameter maybe reset easily by modifying its channel set value, in accordance withfor example, IEEE 802.11, Paragraph 7.3.2.4 “DSS Parameter Set Element”as described in greater detail herein below.

Thus frequency translating repeater 200 in accordance with one ofvarious alternative exemplary embodiments, may convert the 802.11bmodulated packet from a first frequency channel to a second frequencychannel, where it may be received by one or more clients, such asstation devices (STA) or client units 104 or 105. Client units 104 or105 preferably receive a beacon identifying an 802.11b channel as beingthe appropriate channel for communication, and would receive informationpackets translated by the repeater 200 from the “a” band used by AP 100to the “b” band. It will be appreciated by one of ordinary skill in theart that an exemplary frequency translating repeater in accordance withvarious exemplary and alternative exemplary embodiments may translatebetween any 2 channels, such as from an 802.11a channel to another802.11a channel, 802.11a channel to an 802.11b channel, 802.11b channelto an 802.11a channel, 802.11b channel to another 802.11b channel, andso on. It is further contemplated that an 802.11g channel or a channelassociated with any suitable wireless protocol may also be used inaccordance with frequency translation, without departing from theinvention.

On the return signal path, station client unit 105 may transmit thestandard compliant 802.11b signal in the appropriate frequency band,e.g. as defined in the standard, and repeater 200 detects the 802.11bsignal and translates packets carried thereon to frequency channelsdefined in the 802.11a standard, but not conforming to the 802.11a OFDMmodulation. AP 100 may receive the 802.11b modulated waveform in thefrequency channels defined for 802.11a signals, and will process thewaveform it as if it were in a 802.11b frequency channel.

Thus as can be seen from the above, AP 100 uses an IEEE 802.11bmodulation compliant waveform, but transmits signals on a nonstandard-conforming band, e.g. on a different band from one defined asappropriate by the IEEE 802.11b standard. A frequency translatingrepeater 200 in accordance with various exemplary embodiments of thepresent invention, converts the 802.11b modulated packet from the “a”band on one channel to the “b” band on another channel where it is usedby a station device such as client unit 105. When signals return from astation, e.g. client unit 104 or 105 to AP 100, client units 104 or 105may preferably transmit the standard 802.11b compliant signal in theappropriate band, e.g. as defined in the standard, repeater 200 detectsthe 802.11b signal and translates it in accordance with frequencychannels defined in the 802.11a standard, but in conflict with, forexample, the channel of operation, if present, in the DS parameter setmessage.

It will be appreciated that in order to perform frequency translation tochannels in different bands, a multi-band capability is preferablypresent in one or more of an exemplary AP, frequency translatingrepeater, client station or the like node of an exemplary WLAN. Such amulti-band capability preferably allows, for example, both 2.4 GHz and 5GHz waveforms to be generated and transmitted and detected and receivedthrough the use of appropriate hardware such as antennae, power controlcircuits, transceivers, and control software within the same device ornode.

In accordance with various exemplary embodiments of the presentinvention, AP 100 preferably deliberately transmits signals on afrequency different from the frequency identified for transmission inthe beacon signal (channel identifier). Two significant benefits resultfrom deliberate “spoofing” within the beacon message in one band, thentranslating to the specific band in the message. First, as described ingreater detail below, translating can keep back haul channels to/from arepeater open and free from client traffic, allowing capacity to bedistributed among repeaters where needed. Second, translating can allowthe DS parameter message to be correct once it is translated to theintended channel via the repeater 200, allowing correct and standardcompliant operation with client units 104 and 105 from any manufacturer.

It should be noted that in accordance with various exemplary andalternative exemplary embodiments, for example as illustrated in FIG. 2,a back haul channel may refer to the channel with the incorrect DSParameter set message and a translating repeater may be referred to asoff-ramp repeater 204. FIG. 2 further shows hi-way repeater 200 andoff-ramp repeater 204 with three distinct channels of operation: channel201 between AP 100 and hi-way repeater 200, interim channel or off-rampchannel 202 between hi-way repeater 200 and off-ramp repeater 204, andlocal channel 203 between off-ramp repeater 204 and client unit 105.

It should be noted that one or more repeaters such as hi-way repeater200 and off-ramp repeater 204 may connect to any specific backhaul oroff-ramp channel allowing an increase in coverage for any given AP 100,as communication with stations (STA), client units, or the like could beextended to the radiated foot print potentially including a plurality ofrepeaters rather than just a single repeater. It is further important tonote that hi-way repeater 200 and off-ramp repeater 204 simply translateand rebroadcast information packets as well as beacon informationthereby making them similar to repeaters described in co-pending PCTApplication No. PCT/US03/16208.

Before describing the operation of an exemplary embodiment in accordancewith FIG. 2, it must be understood that the present invention may beused in an environment where present wireless local area standards areused. As defined, for example, in the 1999 IEEE 802.11 wirelessstandards and as further shown in Table 1 herein below, paragraphs15.4.6.2 and 18.4.6.2, all the channels defined for transmission withthe DS parameter are in the 2.4 GHz band. TABLE 1 X′10′ X′20′ X′30′X′31′ X′32′ X′40′ CHNL-ID Freq FCC IC ETSI Spain France MKK 1 2412 MHz XX X 2 2417 MHz X X X 3 2422 MHz X X X 4 2427 MHz X X X 5 2432 MHz X X X6 2437 MHz X X X 7 2442 MHz X X X 8 2447 MHz X X X 9 2452 MHz X X X 102457 MHz X X X X X 11 2462 MHz X X X X X 12 2467 MHz X X 13 2472 MHz X X14 2477 MHz X

In contrast, more recently allowed bands under, for example, FederalCommunications Commission code part 15.407, signals are transmitted inthe 5 GHz band. Thus in accordance with various exemplary embodiments ofthe present invention, signals on the backhaul channel, for example,between AP 100 and repeater 200 are preferably at 5 GHz, and may befrequency translated from the 5 GHz band to a channel in the 2.4 GHzband, for example, as specified in the DS parameter set message inrepeater 204. Note that stations receiving a message with an incorrectchannel number, will generally reject the messages on that channel.

In accordance with various exemplary embodiments, AP 100, hi-wayrepeater 200 and off-ramp repeater 204 will all preferably bepre-programmed to communicate with each other on identified channels.Considering, by way of illustration, an exemplary embodiment where, inaccordance with the IEEE 802.11a standard, twelve channels at 5 GHz areused and, in accordance with the IEEE 802.11b standard, six channels at2.4 GHz are used, a system, for example, as shown in FIG. 2, can operateas follows. AP 100 is preferably programmed to transmit and receiveinformation signals on channel 6 in the 5 GHz band. Beacon signals wouldalso be transmitted on channel 6 of the 5 GHz band, but the channelidentifier would be channel 1 of the 2.4 GHz band.

Hi-way repeater 200 is preferably able to receive information packetsand beacon signals on channel 6 and retransmit those signals on channel8 of the 5 GHz band. Off-ramp repeater 204 is preferably set up toreceive on channel 8 of the 5 GHz band and retransmit on, for example,channel 1 in the 2.4 GHz band. It should be noted that accordingly,beacon signals from AP 100, translated from channel 6 in the 5 GHz bandto channel 1 in the 2.4 GHz band by repeater 204, would correctlyidentify channel 1 in the 2.4 GHz band as the correct channel forcommunication.

Further, for signals transmitted from client unit 105 destined for AP100, repeater 204 preferably receives on channel 1 in the 2.4 GHz bandand transmits on channel 8 of the 5 GHz band. Signals from off-ramprepeater 204 transmitted on channel 8 of the 5 GHz band are received byhi-way repeater 200 and retransmitted on channel 6 of the 5 GHz bandwhere AP 100 receives signals on channel 6 of the 5 GHz band.

As will be appreciated from the above description, repeaters operate todetect signals on one of two channels and retransmit the signals on theother channel as described in detail in co-pending PCT Application No.PCT/US03/16208. Thus off-ramp repeater 204 and hi-way repeater 200, forexample, must be pre-programmed, whether in the field (preferable),during manufacture, or the like, for appropriate channels of operation.One of ordinary skill in the art will recognize that repeaters 200 and204 and AP 100 could be programmed to communicate on boot-up or re-bootwith each other and establish channels of operation. Specifically, theAP 100 could transmit control signals to repeaters 200, 204 to establishchannels of operation.

Several additional advantages become apparent using the above systemstructure. For example, many back haul channels such as back haulchannel 201 may be established between different APs or an AP withmulti-channel capability opening significantly expanded capability forone or more off-ramp repeaters such as off-ramp repeater 204.Specifically, by monitoring activity on various channels of operation,an assessment of the traffic load may be made, both in the localstation, e.g. the area in which client unit 105 is located, as well ason any back haul channel. Off-ramp repeater 204 can choose the best backhaul channel for the local load allowing, for example, two heavilyutilized repeaters to “choose” different back haul channels and thusprovide a load leveling feature. It will be appreciated that in order tobalance loads in such a manner, information associated with whichbackhaul channels are intended for which local station channels, e.g.which channels to client unit 105, must be stored in one or more ofhi-way repeater 200, off-ramp repeater 204, and AP 100 using, forexample, a table matching stations or client units to various repeaters,a constant translation distance, or some other mathematical rule formapping.

Exemplary protocol units for sending the beacon, DS, and probe messagesare shown in FIG. 3A and FIG. 3B. Protocol unit 300 may include anelement ID 301 to identify the element being specified by the message,length 302 indicates the length of the variable length informationcontained in information 303. Such a format may be used, for example,for beacon and probe messages which are further governed by the IEEE802.11 standard, e.g. section 7.2.3.1 and 7.2.3.9 respectively of the1999 Edition as will be appreciated by those of ordinary skill. Asfurther illustrated in FIG. 3B, protocol unit 310, which is preferably aDS parameter set element, may include element ID 311, which is specifiedas a value of 3 for DS parameter set purposes, length 312, and currentchannel 313, which channel may be selected according to, for example,values in Table 1, or other values as would be appreciated by those ofordinary skill in the art.

It should be noted that variations and alternative exemplary embodimentsin accordance with the present invention, for example, as illustrated inFIG. 4, may include translating from one channel in the 5 GHz to anotherchannel in the 5 GHz band using an 802.11a modulation wave form. DSparameter message 410 may be optionally used in such a case where thechannel specification must be “spoofed” by AP 100 as described above.Accordingly, channel number 413 specified in DS parameter message 410reflects the correct channel number after translation to the finalfrequency intended as the receiving channel for the client unit 105. Inaccordance with another alternative exemplary embodiment, signals arepreferably transmitted from one 802.11b channel to another 802.11bchannel. The DS parameters message in such an instance will be spoofedto allow for proper operation of client unit 105 and 802.11b modulationwould be used throughout the system.

Still other techniques in accordance with alternative exemplaryembodiments, allow operation on back haul channel 201, off-ramp channel202, and local channel 203. Accordingly, AP 100 may preferably send morethan one probe response or more than one beacon, with a DS Parametermessage defined for each of the channels of operation. In this way,client unit 105 may operate on any of the channels where signal ispresent. Further, while various exemplary embodiments of the presentinvention are described herein in the context of existing standards,such as 802.11a and 802.11b, techniques maybe practiced in anenvironment with different standards without departing from the presentinvention. Thus the invention is described herein in detail withparticular reference to presently preferred embodiments. However, itwill be understood that variations and modifications can be effectedwithin the scope and spirit of the invention.

1. A method for extending the range of a wireless local area network(WLAN), the WLAN including a base unit connected to a wide area network,the base unit communicating with at least one client unit using aprotocol requiring the base unit and the at least one client unit toreceive and transmit information on a same frequency chosen from atleast two available frequencies, the base unit identifying which of theat least two available frequencies is chosen in a control parametertransmitted in a protocol message associated with the protocol, themethod comprising: transmitting a modified control parameter so that thechosen one of the at least two available frequencies does not correspondto a channel upon which the base unit is operating, setting a receivechannel associated with the client unit to match the chosen one of theat least two available frequencies in the control parameter transmittedby the base unit, and translating a first information signal transmittedfrom a first operating channel associated with the base unit andretransmitting the information signal on a second operating channel tothe client unit, and translating a second information signal transmittedfrom the second operating channel associated with the client unit andretransmitting the second information signal on the first operatingchannel associated with the base unit.
 2. The method according to claim1, further comprising modifying the control parameter such that adifferent one of the at least two available frequencies is identified aschosen.
 3. The method according to claim 1, wherein the base unit isconnected to a wired wide area network.
 4. The method according to claim1, wherein the base unit is connected to a wireless wide area network.5. The method according to claim 1, wherein the protocol includes oneof: 802.11a, 802.11b, 802.11a, 802.11g, Bluetooth, TDS-CDMA, TDD-W-CDMA,802.16, and 802.20.
 6. The method according to claim 1, wherein thetranslation is performed on an unscheduled basis.
 7. In a wirelessnetwork including one or more base units and one or more client units,the one or more base units capable of transmitting on a first one of theat least two frequency channels and the one or more client units capableof transmitting on a second one of the at least two frequency channels,each of the one or more base units capable of transmitting a channelidentifier, an apparatus for enhancing coverage of the wireless network,comprising: a frequency translating repeater configured to: receive thechannel identifier identifying the second one of the at least twofrequency channels as a designated channel for communicating with theone or more base units; detecting a first information signal from theone or more base units on the first one of the at least two frequencychannels and retransmitting the first information signal on the secondone of the at least two frequency channels in accordance with thechannel identifier; and detecting a second information signal from theone or more client units on the second one of the at least two frequencychannels and retransmitting the second information signal on the firstone of the at least two frequency channels in accordance with thechannel identifier.
 8. The apparatus according to claim 7, wherein thefirst one of the at least two frequency channels includes a 5 GHz bandfrequency channel in accordance with the IEEE 802.11a standard.
 9. Theapparatus according to claim 8, wherein the second one of the at leasttwo frequency channels includes a 2.4 GHz band frequency channel inaccordance with the IEEE 802.11b standard.
 10. The apparatus accordingto claim 7, wherein the channel identifier includes a direct sequence(DS) parameter signal in accordance with the IEEE 802.11 standard. 11.The apparatus according to claim 7, wherein each of the one or more baseunits is configured to transmit the channel identifier identifying thebase unit as transmitting a IEEE 802.11b modulation waveform, andwherein the first one of the at least two frequency channels includes a5 GHz band in accordance with the IEEE 802.11a standard.
 12. Theapparatus according to claim 11, wherein the frequency translatingrepeater is configured to translate the 802.11b modulated waveform fromthe 5 GHz band to the second one of the at least two frequency channelsand wherein the second one of the at least two frequency channelsincludes a 2.4 GHz band in accordance with the IEEE 802.11b forretransmission to the one or more client units.
 13. The apparatusaccording to claim 12, wherein the frequency translating repeater isconfigured to detect the second information signal on the second one ofthe at least two frequency channels at the 2.4 GHZ band from the clientunit, and to retransmit the second information signal at the first oneof the at least two frequency channels, the frequency translatingrepeater configured to retransmit the second information signal in amodulation format which modulation format does not conform to the802.11a orthogonal frequency division modulation (OFDM) standard.
 14. Ina wireless network including at least two frequency channels, one ormore base units and one or more client units, the one or more base unitscapable of transmitting on the first one of the at least two frequencychannels and the one or more client units capable of transmitting on thesecond one of the at least two frequency channels, the one or more baseunits capable of transmitting a channel identifier identifying thesecond one of the at least two frequency channels as a designatedchannel for communicating with the one or more base units, an apparatusfor enhancing coverage of the wireless network, comprising: a firstwireless repeater unit and a second wireless repeater unit formonitoring the at least two frequency channels and retransmitting afirst information signal received on a first one of the at least twofrequency channels on a second one of the at least two frequencychannels, wherein the first wireless repeater unit is configured to:receive the first information signal from the one or more base units onthe first one of the at least two frequency channels; retransmit thefirst information signal on a third frequency channel; and detect andreceive the first information signal from the second wireless repeaterunit on the third frequency channel, and retransmit the firstinformation signal on the first one of the at least two frequencychannels, and wherein the second wireless repeater unit is configuredto: detect and receive the first information signal from the firstwireless repeater unit on the third frequency channel; and retransmitthe first information signal on the second one of the at least twofrequency channels, and detect and receive the first information signalfrom the one or more client units on the second one of the at least twofrequency channels and retransmit the first information signal on thethird frequency channel.
 15. The apparatus according to claim 14,wherein the channel identifier includes a DS parameter signal inaccordance with the IEEE 802.11 standard.
 16. The apparatus according toclaim 14, wherein the first wireless repeater unit is configured tomonitor a traffic load associated with the first of the at least twofrequency channels to establish a load level measurement, and choose oneof the second and the third frequency channels for communicating withthe one or more base units to equalize the traffic load based on theload level measurement.
 17. The apparatus according to claim 16, whereinthe load level measurement includes a determination of which of one ormore of the first, second and additional frequency channels has a lowestdetected value associated with the traffic load.
 18. The apparatusaccording to claim 16, wherein the load level measurement is determinedby the traffic load associated with the one or more client unitsrelative to the second wireless repeater unit.
 19. The apparatusaccording to claim 16, wherein the first wireless repeater unit isconfigured to determine which of the first, the second, and the thirdfrequency channels intended for specific ones of the one or more clientunits based on a contents of one or more DS parameter messages.
 20. Theapparatus according to claim 19, wherein the first wireless repeaterunit further includes a memory and is configured to determine usinginformation stored as a table in the memory.
 21. The apparatus accordingto claim 19, wherein the first wireless repeater unit further includes amemory and is configured to determine using a rule stored in the memory.22. The apparatus according to claim 19, wherein the first wirelessrepeater unit further includes a memory and is configured to determineusing a stored constant offset stored in the memory.
 23. The apparatusaccording to claim 14, wherein the second wireless repeater unit isconfigured to monitor a traffic load associated with the second of theat least two frequency channels to establish a load level measurement,and choose one of the second and the third frequency channels forcommunicating with the one or more base units to equalize the trafficload based on the load level measurement.
 24. The apparatus according toclaim 23, wherein the load level measurement includes a determination ofwhich of one or more of the first, second and third frequency channelshas a lowest detected value associated with the traffic load.
 25. Theapparatus according to claim 23, wherein the load level measurement isdetermined by the traffic load associated with the one or more clientunits relative to the first wireless repeater unit.
 26. The apparatusaccording to claim 23, wherein the second wireless repeater unit isconfigured to determine which of the first, the second, and the thirdfrequency channels intended for specific ones of the one or more clientunits based on a contents of one or more DS parameter messages.
 27. Theapparatus according to claim 26, wherein the second wireless repeaterunit further includes a memory and is configured to determine usinginformation stored as a table in the memory.
 28. The apparatus accordingto claim 26, wherein the second wireless repeater unit further includesa memory and is configured to determine using a rule stored in thememory.
 29. The apparatus according to claim 26, wherein the secondwireless repeater unit further includes a memory and is configured todetermine using a stored constant offset stored in the memory.